Question

You know that H is dominant for height locus and H is recessive. Is the F2 progeny are a mixture of 3:1 dominant: recessive and you pick a dominant plant at random what will be the probability that the F3 will have a mixture of dominant and recessive traits as well?

(a) All will show

(b) 1/16

(c) 1/4

(d) 2/3

The question was posed to me in a national level competition.

My question is based upon Numerical Problems in chapter Mendelian Genetics of Cytogenetics

Answer 1

The correct option is (d) 2/3

Explanation: Here we are actually selecting the plants which are heterozygous for the trait as in Hh. Only selfing these will give both dominant and recessive trait in next generation. As we are not taking hh into consideration the ratio resulting is 2/3.